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Rennie Spearmint Heartburn & Indigestion Relief 72 Tablets

Rennie Spearmint Heartburn & Indigestion Relief 72 Tablets

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  • ✔️ Neutralises excess stomach acid to relieve heartburn fast
  • ✔️ Contains calcium carbonate and magnesium carbonate antacids
  • ✔️ Suitable for adults and children aged 12 and over
  • ✔️ Pleasant spearmint flavour — chewable for easy, on-the-go use
  • ✔️ 72-tablet pack provides lasting supply for frequent sufferers

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What Are Rennie Spearmint Tablets Used For?

 

If you've ever felt that uncomfortable burning sensation rising in your chest after a meal, you'll know how disruptive heartburn can be. Rennie spearmint tablets are a well-established, over-the-counter antacid medicine designed to relieve heartburn, acid indigestion, and upset stomach quickly and effectively. Each pack contains 72 tablets, making it a practical option for anyone who experiences these symptoms regularly. At just £6.39, it's an accessible choice for everyday digestive discomfort. You can browse our full range of indigestion treatments if you'd like to compare your options.

Heartburn affects a significant proportion of the UK population. According to the NHS, it's a very common condition — often triggered by certain foods, alcohol, pregnancy, or simply lying down after eating. Rennie has been used for decades as a trusted antacid, and the spearmint flavour makes the tablets pleasant to chew or suck, which can be a real bonus when you're already feeling uncomfortable.

 

How Do Rennie Spearmint Tablets Work?

 

Rennie works through a straightforward chemical process. The active ingredients — calcium carbonate and heavy magnesium carbonate — are antacids that react with excess stomach acid to neutralise it. This reduces the acidity in your stomach and oesophagus, easing that burning feeling relatively quickly.

  • Calcium carbonate (680 mg per tablet) reacts with hydrochloric acid in the stomach to form calcium chloride, water, and carbon dioxide.
  • Heavy magnesium carbonate (80 mg per tablet) works alongside calcium carbonate to provide a balanced antacid effect.
  • Together, these ingredients raise the pH of stomach contents, reducing irritation to the oesophageal lining.
  • The tablets are chewed or sucked, allowing the active ingredients to begin working in the mouth and upper digestive tract.

Unlike proton pump inhibitors (PPIs) or H2 blockers, antacids like Rennie don't reduce the amount of acid your stomach produces — they simply neutralise what's already there. This means they act quickly but for a shorter duration.

 

Who Should Use Rennie Spearmint Tablets?

 

These tablets are suitable for a wide range of people dealing with occasional digestive discomfort. They're particularly useful if you need fast, on-the-spot relief without a prescription. That said, they're not appropriate for everyone, so it's worth checking the suitability criteria before you start.

  • Adults and children aged 12 and over experiencing heartburn or acid indigestion
  • Pregnant women with occasional heartburn (always check with your midwife or GP first)
  • People who prefer a chewable, flavoured tablet over liquid antacids
  • Those looking for a convenient, portable option for managing symptoms after meals or at bedtime

They are not suitable for children under 12, or for people with severely impaired kidney function. If you're unsure whether Rennie is right for you, speak to your pharmacist before use.

 

How Do Rennie Spearmint Tablets Compare to Other Antacids?

 

Feature Rennie Spearmint 72 Tablets Gaviscon Advance Liquid
Mechanism Neutralises stomach acid Forms a raft barrier over stomach contents
Form Chewable tablet Liquid suspension
Suitable for pregnancy Generally yes (seek advice) Generally yes (seek advice)
Active ingredients Calcium carbonate, magnesium carbonate Sodium alginate, potassium bicarbonate

 

How Should You Store Rennie Spearmint Tablets?

 

Store your Rennie spearmint tablets below 25°C in a dry place, away from direct sunlight. Keep them out of reach and sight of children at all times. Do not use the tablets after the expiry date printed on the packaging. If you're also managing other digestive concerns, you might find our IBS and cramps collection useful for complementary products.

This product is a medicine. Speak to your doctor or pharmacist before using if you have an underlying medical condition or are taking other medicines.

Rennie Spearmint Heartburn & Indigestion Relief 72 Tablets specifications
Treatment category Heartburn & Indigestion
Mechanism of action Neutralises excess stomach acid
Effective for Heartburn, acid indigestion, upset stomach
Suitable for Adults and children aged 12 and over
Active ingredient Calcium carbonate 680 mg, Heavy magnesium carbonate 80 mg
Pack size 72 tablets
UK classification General Sale List (GSL)
Drug class Antacid
Preparation Chewable tablet
Route of administration Oral

Specifications of Rennie Spearmint Heartburn & Indigestion Relief 72 Tablets

 

What Is Rennie Spearmint and What Is It Used For?

 

Rennie Spearmint Heartburn & Indigestion Relief tablets are an antacid medicine used to treat the symptoms of heartburn, acid indigestion, and upset stomach. Each tablet contains two active ingredients — calcium carbonate 680 mg and heavy magnesium carbonate 80 mg — which work together to neutralise excess stomach acid. The NHS describes heartburn as a burning feeling in the chest caused by stomach acid travelling up towards the throat, and it's one of the most common digestive complaints in the UK. These tablets are available without a prescription and are classified as a General Sale List (GSL) medicine.

The spearmint flavour makes them easy and pleasant to take, particularly when you're already feeling unwell. They're intended for short-term, symptomatic relief — not as a long-term solution to persistent acid problems. If your symptoms keep coming back, it's worth speaking to your GP to rule out any underlying cause.

 

What Do You Need to Know Before Using Rennie Spearmint?

 

Before taking these tablets, read the following carefully. There are certain situations where Rennie Spearmint may not be appropriate.

Do not take Rennie Spearmint if you:

  • Are allergic to calcium carbonate, magnesium carbonate, or any other ingredient in the tablets
  • Have severely impaired kidney function (renal failure)
  • Have hypercalcaemia (high levels of calcium in the blood)
  • Are under 12 years of age
  • Have been diagnosed with nephrolithiasis (kidney stones related to calcium)

Speak to your pharmacist or GP before use if you:

  • Are pregnant or breastfeeding
  • Have kidney disease or reduced kidney function
  • Are taking other medicines regularly
  • Have symptoms that could suggest a more serious condition (e.g. difficulty swallowing, unexplained weight loss, persistent vomiting)

Known drug interactions — leave at least 2 hours between Rennie and:

  • Tetracycline antibiotics (e.g. doxycycline)
  • Iron supplements
  • Some antifungal medicines (e.g. ketoconazole)
  • Bisphosphonates (e.g. alendronic acid)
  • Thyroid medicines (e.g. levothyroxine)

 

How Should You Use Rennie Spearmint Tablets?

 

Always use this medicine exactly as described in the patient information leaflet or as directed by your pharmacist. Do not swallow the tablets whole — they should be chewed or sucked.

  1. Take 2 tablets when symptoms occur, after meals, or at bedtime.
  2. Chew or suck the tablets — do not swallow them whole.
  3. Allow the tablet to dissolve fully in your mouth before swallowing.
  4. Do not take more than 3 doses (6 tablets) in any 24-hour period.
  5. If symptoms persist beyond 7 days, stop use and consult your GP.
Age Group Dose Frequency Maximum Daily Dose
Adults & children 12+ 2 tablets After meals and at bedtime, or when symptoms occur 6 tablets (3 doses)
Children under 12 Not recommended

 

What Are the Possible Side Effects of Rennie Spearmint?

 

Like all medicines, Rennie Spearmint can cause side effects, although not everyone experiences them. Most people tolerate antacids well when taken at the recommended dose.

Common side effects:

  • Constipation (more likely with calcium-containing antacids)
  • Diarrhoea (more likely with magnesium-containing antacids)
  • Flatulence (wind)

Less common side effects:

  • Nausea
  • Stomach cramps
  • Hypercalcaemia (raised blood calcium) — particularly with prolonged high-dose use
  • Milk-alkali syndrome — a rare condition associated with excessive calcium carbonate intake alongside dairy products

If you notice any side effects not listed here, or if any listed side effects become severe, stop taking the tablets and speak to your pharmacist or GP. You can also report side effects directly to the MHRA via the Yellow Card scheme. If you're managing related digestive symptoms, our sickness and nausea range may also be of interest.

 

How Should You Store Rennie Spearmint Tablets?

 

  • Store below 25°C in a dry place
  • Keep away from direct sunlight and moisture
  • Keep out of reach and sight of children
  • Do not use after the expiry date printed on the carton
  • Do not dispose of medicines via wastewater or household waste — return unused tablets to your pharmacy

If you're looking for additional support with digestive health, you might also want to explore our vitamins and supplements collection for products that support gut wellbeing.

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Your safety and success are our highest priorities. Our medical team rigorously evaluates every product and piece of advice we provide, ensuring you receive only the most effective, science-backed solutions available.

Frequently Asked Questions

Where can I buy Rennie Spearmint tablets online in the UK?

You can buy Rennie Spearmint 72 tablets directly from Cured Pharmacy, a GPhC-registered UK online pharmacy, with fast delivery to your door. They are also widely available from supermarkets and high street pharmacies without a prescription. Buying online is a convenient option if you want to stock up on a larger pack size like the 72-tablet pack.

How do Rennie Spearmint tablets work in the body?

Rennie Spearmint tablets contain calcium carbonate and heavy magnesium carbonate, two antacids that chemically neutralise excess stomach acid on contact. This raises the pH of your stomach contents, reducing the burning sensation caused by acid reflux or indigestion. Unlike some other heartburn medicines, antacids work quickly because they act directly in the stomach rather than altering acid production.

How do I use Rennie Spearmint tablets step by step?

Chew or suck 2 tablets when your symptoms occur — typically after meals or at bedtime. Do not swallow them whole, as the tablets need to dissolve in your mouth and upper digestive tract to work properly. You can take up to 3 doses (6 tablets) in a 24-hour period, but do not exceed this amount.

What is the correct dose of Rennie Spearmint for adults?

The recommended adult dose is 2 tablets per episode, taken after meals or at bedtime, or whenever symptoms arise. The maximum dose is 6 tablets in any 24-hour period — that's no more than 3 separate doses. If you find you're regularly reaching the maximum dose, speak to your GP as this may suggest an underlying issue.

Can I take Rennie Spearmint tablets during pregnancy?

Rennie is generally considered one of the more suitable antacid options for occasional heartburn during pregnancy, as heartburn is extremely common in the second and third trimesters. However, you should always check with your midwife, GP, or pharmacist before taking any medicine while pregnant, as individual circumstances vary. Do not take high doses or use for prolonged periods without medical guidance.

Are Rennie Spearmint tablets suitable for children?

Rennie Spearmint tablets are only suitable for adults and children aged 12 and over. They should not be given to children under 12 years of age. If your child is experiencing digestive discomfort, speak to your GP or pharmacist for age-appropriate treatment options.

What are the side effects of Rennie Spearmint tablets?

Most people tolerate Rennie Spearmint well, but some may experience constipation, diarrhoea, or flatulence. Less commonly, nausea or stomach cramps can occur. If you experience any unusual or persistent symptoms, stop taking the tablets and speak to your pharmacist or GP.

Can Rennie Spearmint tablets interact with other medicines?

Yes — antacids can affect the absorption of several medicines, including tetracycline antibiotics, iron supplements, bisphosphonates, levothyroxine, and some antifungal medicines. To avoid this, leave at least 2 hours between taking Rennie and any other medication. Always tell your pharmacist about all medicines you're currently taking before starting a new one.

How long can I take Rennie Spearmint tablets for?

Rennie Spearmint is intended for short-term relief of occasional heartburn and indigestion. If your symptoms persist for more than 7 days, or if they worsen, you should stop taking the tablets and consult your GP. Persistent heartburn can sometimes indicate an underlying condition such as gastro-oesophageal reflux disease (GORD) that requires a different approach to treatment.

What happens if I take too many Rennie Spearmint tablets?

Taking more than the recommended dose can lead to side effects such as constipation, nausea, or in rare cases, hypercalcaemia (raised blood calcium levels). If you accidentally take too many tablets, contact NHS 111 or your nearest A&E for advice. Always keep medicines out of reach of children to prevent accidental ingestion.

What are the alternatives to Rennie Spearmint tablets?

There are several alternatives available for heartburn and indigestion, including other antacids (such as Gaviscon), H2 blockers (such as famotidine), and proton pump inhibitors (such as omeprazole). You can explore our full indigestion treatments range to compare options. The right choice depends on the frequency and severity of your symptoms, so speak to your pharmacist if you're unsure.

What is the best time to take Rennie Spearmint tablets?

Rennie Spearmint tablets work best when taken after meals and at bedtime, as these are the times when stomach acid is most likely to cause discomfort. You can also take them as soon as symptoms appear at any time of day. Taking them on an empty stomach is less effective, as there's less acid to neutralise.

Do Rennie Spearmint tablets contain any allergens or animal products?

Rennie Spearmint tablets contain sucrose and glucose syrup, so they are not suitable for people with rare hereditary conditions such as fructose intolerance or glucose-galactose malabsorption. The tablets are not classified as vegan due to the presence of certain excipients — check the patient information leaflet for the full list of ingredients. If you have specific dietary concerns, speak to your pharmacist before use.

Can I take Rennie Spearmint tablets with food or drink?

Yes — in fact, taking Rennie after meals is one of the recommended times for use, as food can trigger acid production. You don't need water to take them since they're chewed or sucked rather than swallowed whole. Avoid taking them alongside large amounts of dairy products if you're using them frequently, as this combination can rarely cause a condition called milk-alkali syndrome.

What are the latest guidelines on treating heartburn in the UK?

The NHS recommends lifestyle changes as the first step in managing heartburn — including eating smaller meals, avoiding trigger foods, not lying down after eating, and maintaining a healthy weight. Antacids like Rennie are recommended for occasional, mild symptoms. For frequent or severe heartburn, the NHS advises speaking to a GP, who may recommend a prescription-strength medicine such as a PPI. You can also explore our pain relief collection for other symptom management options.

How Should You Use Rennie Spearmint Tablets?

Rennie Spearmint tablets are designed to be chewed or sucked — never swallowed whole. Allowing the tablet to dissolve in your mouth means the active ingredients can begin working in the upper digestive tract as quickly as possible. Follow these steps each time you take a dose:

If you're taking other medicines, leave at least 2 hours between Rennie and your other medication to avoid any interaction affecting absorption.

What Is the Correct Dose of Rennie Spearmint Tablets?

The correct dose depends on your age. Only adults and children aged 12 and over should use these tablets. Always stick to the recommended dose and do not take more than 6 tablets in any 24-hour period, regardless of how severe your symptoms feel.

When Is the Best Time to Use Rennie Spearmint Tablets?

The most effective times to take Rennie Spearmint are after meals and at bedtime, as these are the periods when stomach acid is most likely to cause discomfort. Eating stimulates acid production, and lying down can allow acid to travel upwards into the oesophagus more easily. Taking a dose at bedtime can help prevent night-time heartburn that might otherwise disturb your sleep. You can also take a dose as soon as symptoms appear at any point during the day — there's no need to wait.

How Long Can You Use Rennie Spearmint Tablets For?

These tablets are intended for short-term, occasional use only. If your symptoms have not improved after 7 days of use, or if they worsen at any point, you should stop taking the tablets and speak to your GP. Persistent or frequent heartburn may indicate an underlying condition such as gastro-oesophageal reflux disease (GORD), which requires a different treatment approach. Long-term, high-dose use of calcium-containing antacids is not recommended without medical supervision, as it can lead to raised calcium levels in the blood.

Do not exceed the recommended dose. If in doubt, speak to your pharmacist.

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What Are the Most Common Side Effects of Rennie Spearmint Tablets?

Most people who take Rennie Spearmint at the recommended dose experience no side effects at all. However, as with any medicine, some people may notice mild digestive changes. These are generally short-lived and resolve on their own once you stop taking the tablets.

  • Constipation — more likely with calcium carbonate-containing antacids
  • Diarrhoea — more likely with magnesium carbonate-containing antacids
  • Flatulence (wind)

What Are the Less Common Side Effects of Rennie Spearmint Tablets?

Less frequently, some people may experience the following. If any of these occur and are troublesome, stop taking the tablets and speak to your pharmacist or GP.

  • Nausea
  • Stomach cramps or abdominal discomfort
  • Belching
  • Changes in bowel habits

What Are the Serious Side Effects of Rennie Spearmint Tablets?

Serious side effects are rare when Rennie is taken at the recommended dose for short periods. However, taking too many tablets over a prolonged period can lead to hypercalcaemia — a condition where calcium levels in the blood become too high. Symptoms of hypercalcaemia include nausea, vomiting, weakness, confusion, and increased thirst. In very rare cases, excessive use of calcium carbonate alongside large amounts of dairy products can cause milk-alkali syndrome, which can affect kidney function. If you experience any of these symptoms, stop taking the tablets immediately and seek medical attention.

What Should You Do If You Experience Side Effects?

If you notice any side effects that concern you, stop taking Rennie Spearmint and speak to your pharmacist or GP as soon as possible. For mild side effects such as constipation or wind, reducing your dose or stopping use is usually sufficient. If you suspect a serious reaction — such as signs of hypercalcaemia — seek urgent medical advice. You can also report any suspected side effects directly to the Medicines and Healthcare products Regulatory Agency (MHRA) via the Yellow Card scheme at yellowcard.mhra.gov.uk. This helps improve medicine safety for everyone.

Can Rennie Spearmint Tablets Interact With Other Medicines?

Yes — antacids can interfere with the absorption of several other medicines, which is an important consideration if you take regular medication. The calcium and magnesium in Rennie can bind to certain drugs in the gut, reducing how much of the medicine gets into your bloodstream. To minimise this risk, always leave at least 2 hours between taking Rennie and any of the following:

  • Tetracycline antibiotics (e.g. doxycycline, tetracycline)
  • Iron supplements
  • Bisphosphonates (e.g. alendronic acid, used for osteoporosis)
  • Levothyroxine (thyroid hormone replacement)
  • Some antifungal medicines (e.g. ketoconazole, itraconazole)
  • Some HIV medicines

Always tell your pharmacist about all medicines, supplements, and herbal remedies you are taking before starting Rennie Spearmint.

If you are concerned about any side effects, contact your pharmacist or GP immediately.

Patient Information Leaflet

Important - Before taking any medication, it is always important to read the Patient Information Leaflet (PIL)

Written and reviewed by our qualified team

GPhC Number: 2233073
Tarun Kumar

Reviewed by:

Tarun Kumar

Superintendent/ Clinical Lead

📖 Find out more about our team of medical content authors and how we ensure the accuracy of our content with our content guidelines.

Content last updated: 31 Mar 2025

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